Void Contract - A contract obtained by fraud is a void contract. It is not a contract at all. Under this there cannot be any action as no rights or obligations are cast on the parties to the contract.
Voidable Contract - A contract, which is valid until it is treated as void by the aggrieved party, is a voidable contract. Obviously in such an event the insurer would be the aggrieved party and has the option to repudiate liability.